INFRA-RED RAYS

Rotorua Morning Post, Volume 2, Issue 393, 30 November 1932, Page 7

INFRA-RED RAYS

REMARKABLE FEATS IMMENSE POSSIBILITIES OF IMPORTANT DISCOVERY. PENTRATIVE POWERS. Don't touch! that kettle Can/t you see it's hot? Well, hardly, and yet who can say that some day it will not be possible to see whether an article j is hot with tbej aid of special infrared glasses? With the new infra-red plate recently perfected hy the Ilford Co. in England, some remarkable feats of photography have been performed. During the course of a lecture delivered to the Royal Sydney Ph'otographic Society, the audience were p'hotographed in total darkness, with the sole aid of these infra-red rays, which are the totally invisible heat rays of the spectrum. This certainly proves that although we cannot yet see the heat rays emanating from an object, they can now be photographed. What are these infra-red heat rays ? Nearty every person has seen the spectrum in the form of a rainbow, and knows of the invisible ultra-violet rays, with their remarkable healthgiving and sun-tanning properties. Just as these rays are beyond the visible violet end of the spectrum, infra-red rays are beyond th'e visible red end, and are similarly of wavelengths which the eye cannot see. There is nothing unusual in this. Certain sound vibrations are too low and too high for the ear to hear. This has been proved by observers studying certain birds whistling up the scale. Long after the notes are heard th'e birds can be seen whistling still higher notes. Black is White. Now that experiments have proved that heat absorption and reflection can be photographed, some remarkable possibilities are opened up in matters foeverydajp consideratiton. Six different pieces of black material photographed by infra-red plates recorded different densities, ranging from black to write, proving that certain black materials could be equally as cool as white matei'ials. What a boon this will prove to the man who wears dark coloured suitings in summer weather. No need for him to walk around scorching. The tailor's chart may show him dark suitings, nearly as cool as white duck. The Strathnaver and Strathaird were painted white to lower the tropical temperature by 4 degrees. If the shipbuilders had taken advantage of the infra-red plate, some other j colour possibly cooler may have been j discovered. j No wonder it so cool and fresh i under the shade of a tree in hot weather. Photographed with the infra-red j plate, trees are snow white. Every I bit of heat is reffected, and the trees | are as cool as is possible for anyl thing to be undei' a merciless sun. | See Through Walls. ! The criminal of the future will have i to beware as he starts to try the com- ' bination of the safe. Infra-red rays will be switched on simultaneously , with motion pictuna cameras, and the police will have a Hollywood record ! of the offender, caught red-handed on ; the job. The wide-awake gangster will have to be very much awake to disguise characteristics that are totally invisible to the naked eye, and are only revealed to the police photographer with his infra-red plate. The infra-red plate can still do something else besides photograph heat. It can peer through thick fogs that are walls of invisibility to the naked eye, iand the warring nations of the future will not be slow in taking advantage of this remarkable feature. The reason for this is that moisture partieles 'disperse visible light, and eveiy motorist who has driven through a thick fog realises the impotency of headlights that are reflected back on him. In fact, some of the most recent British cars have a fog-p'iereing light fitted, in addition to the n'ormal headlights. The beam from this light is of a distinct orange shade, the colour least reflected by fog, and so far the nearest visible approach to the invisible infra-red. It is interesting to note that the State Governor's car is one of the few cars in Sydney fitted with one of these special fog-piercing lights.